Hello folks!

I know this may have been spoken about many times but I can't seem to find anything on it.

Basically, why and how do people change their BP's to look something like this..

https://gyazo.com/4baf5c3c7ad15fb804b6208435c3953c

Whenever I have looked at the backpacks and how they're arranged, I can't help but think that the set-up is a waste of cap? Or is there a purpose or trick to having your backpacks like this?

Fill me in!

Hope you're all well!
Yours,
BnW.